FULL PRODUCT VERSION :


A DESCRIPTION OF THE PROBLEM :
When window is minimized, d3d present is skipped, hence vsync does not block.

This causes busy message loop pulse->render->pulse when scene changes every frame:

In PresentingPainter
    @Override public void run() {
...
            valid = validateStageGraphics();
            if (!valid) {
...
                return;
            }
... present skipped when minimized ...

    protected boolean validateStageGraphics() {
...
        return sceneState.isWindowVisible() && !sceneState.isWindowMinimized();
    }

PaintCollector.done:
...
if (needsHint && !toolkit.hasNativeSystemVsync()) {
toolkit.vsyncHint();
}
...
QuantumToolkit.vsyncHint:
if (isVsyncEnabled()) {
...
postPulse();
}

There may be other open bugs caused by this problem, like high cpu on minimize, etc.

----------------------------
The following quick fix solves the issue but more elaborate design may be required:

PaintCollector.done:
...
if (needsHint && !toolkit.hasNativeSystemVsync() &&
sceneState.isValid() && sceneState.isWindowVisible()
&& !sceneState.isWindowMinimized()){
toolkit.vsyncHint();
}

Note it relies on the fact that QuantumRenderer is initialized with single thread.

If more info is required please contact fedor.losev@gmail.com


REPRODUCIBILITY :
This bug can be reproduced always.